The overarching goal of the Sampling and Separation Core is to support diverse measurements of signaling peptides and proteins using a range of approaches and then provide these samples to the Protein Identification Core for analysis. The chemical, temporal and spatial diversity of cell-cell signaling molecules requires significant expertise and planning to allow successful peptidomics and proteomics measurements. To profile signaling peptides and proteins in specific brain tissues and cells, this core specializes in: (1) collecting and fractionating peptides and proteins from biological samples, (2) creating directed sampling methodologies for single cells, spatially distinct brain regions, and biological fluids, (3) optimizing sample fractionation approaches including low-volume multidimensional separations, and (4) preparing tissues for mass spectrometry imaging. In cases where protocols and techniques do not exist for to accomplish the measurements goals, the appropriate technologies are developed. This suite of technologies will be applied to profile the signaling peptides and proteins within the nervous system in the study of fundamental neuroscience as well as pathological conditions such as drug-of-abuse-induced changes. Samples range from intact brain regions to single cells, from probing the chemical content of a tissue to measuring the subset that undergoes activity-dependent release, and from acquiring information on spatial to temporal changes in the signaling peptide complement. The core offers the flexibility to individually tailor isolation and separation methodologies for signaling peptides and related proteins inherently unique to the neurobiological phenomena under investigation by each major user.